Harsh weather conditions such as high wind speed have high impact on wind turbines in a wind farm, causing large unbalanced loads on turbine components due to the excessive aero-dynamic power of the wind acting on the wind turbine rotor. Typically, these harsh or extreme conditions are rare but if no mitigation actions are taken to alleviate these loads during such conditions, the turbine components may be damaged or the overall lifetime of the components may be reduced by a significant amount.
It is known to cut-off the wind turbine from the grid or shut down the wind turbine when the wind speed exceeds a predefined wind speed threshold in order not to subject the turbine components to the extreme loads. This shutting down of the wind turbine during high wind is a safety procedure to protect the turbine. When the turbine is shut down due to high wind, it has to be re-started when normal wind condition is detected. The start-up process of the turbine takes a significant amount of time and also consumes power from the grid. Therefore, a substantial amount of power production is lost every time the turbine is shut down due to high wind and re-started when the wind condition returns to normal. Specifically, the period between the time the wind condition returns to normal and the time the turbine is ready to produce power after re-starting can be used for power production. This is especially true when the high wind condition only lasts for a short time, and shutting down the turbine during this transient wind condition seems impractical.
It is desirable to provide a method to allow some of the wind turbines in a wind farm to remain connected to the grid even during high wind condition, as so to reduce loss of power production.